Ovid was born in 43 BCE, and he finished the Metamorphoses around 8 CE, which is the year the emperor Augustus sent him into exile at Tomis, a cold town on the Black Sea. The reason has never been fully explained. Ovid himself blamed "a poem and a mistake". The poem was probably the Art of Love. The mistake, nobody knows. He says that on the night he left he threw a copy of the Metamorphoses on the fire, though other copies were already out in the world. That is lucky for us.
Fifteen books, one idea
The poem begins with a promise to tell of bodies changed into new forms, and it keeps that promise for fifteen books. It starts from the formless chaos at the beginning of the world and ends in Ovid's own time, with Julius Caesar turned into a star, a strong hint that Augustus will join him, and a last boast that Ovid's name will live forever. He was right.
Along the way come a great many of the stories you probably know. Daphne turns into a laurel tree as Apollo reaches for her. Narcissus wastes away over his own reflection, and Echo fades to a voice. Pyramus and Thisbe die on opposite sides of a wall. Arachne is turned into a spider. King Midas gets his golden touch, and Orpheus loses Eurydice. For many readers across many centuries, these were the Greek myths. Shakespeare read Ovid. Titian painted him.
Latin names, Roman manners
He writes Jupiter, Juno, Minerva, Diana. And the gods are different too. They are courtly, vain, easily offended, and very funny. Apollo's pursuit of Daphne begins as petty revenge: Apollo mocks Cupid's skill with a bow, so Cupid shoots him with a gold arrow that makes him fall in love, and Daphne with a lead one that makes her run. It is a joke about a god's ego, told with a straight face. No Greek worshipper at Eleusis would have heard the gods spoken of like that at a rite, and I don't think Ovid expected them to.
Persephone, told again
Compare his Persephone, whom he calls Proserpina, with the old Homeric Hymn. In Ovid the story is sung by a Muse in a singing contest. When the girl is seized, her dress tears open and the flowers she was gathering fall out, and Ovid says that in her childish simplicity she grieved even for the lost flowers. It is a sweet, precise, very Roman detail. The Hymn is about honor and the bargaining between gods. Ovid is about pity. Both are great. They are not doing the same job, and it's worth reading them back to back.
Dionysus and Athena
Two stories in particular are worth knowing. In the third book, the young king Pentheus of Thebes refuses to accept Bacchus, which is Dionysus, as a god, and his own mother tears him apart in a frenzy, thinking he is a wild animal. And in the sixth, the weaver Arachne challenges Minerva, who is Athena, to a contest. Minerva weaves a tapestry of gods punishing mortals who dare to challenge them. Arachne weaves the gods' own misdeeds, the abductions and deceptions, in perfect detail. Ovid says that even the goddess couldn't find a flaw in it. And then she destroys the cloth anyway and strikes the girl. I find that astonishing: Ovid gives the human artist the better work, and lets the goddess lose the argument and win the fight.
How to read it
We file Ovid as a lens, not a rite, and that is what I'd tell any reader. His version of Greek myth is the one most of Europe inherited, since Latin stayed in schools for centuries. But his tone, ironic and playful and always aware of itself, isn't what a Greek would have felt in front of the gods. When you want the ritual, go to the Greek texts. When you want a story told so beautifully you forget to ask whether it's true, go to Ovid.
One last thought, and I hold it loosely. A poem in which everything changes, even the gods, even the shape of a person, might have been a risky thing to write under an emperor who wanted everything to stay put. Maybe that is part of why it reads the way it does. Maybe it isn't. It's our guess, not a fact.